code: def test_run_async(self):
      counter = mp.Value("l", 0)
  
      def run_func(process_idx):
          for _ in range(1000):
              with counter.get_lock():
                  counter.value += 1
  
      async_.run_async(4, run_func)
      self.assertEqual(counter.value, 4000)
  
file_path: pfrl/tests/utils_tests/test_async.py
imports: import multiprocessing
  import os
  import signal
  import sys
  import unittest
  import warnings
  from pfrl.utils import async_
label_desc: Use image node_id 1 for calling the TestAsync obj's underlying member method code with example usage: obj.test_run_async() without return types